| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 5.5° | 0.4° | 57.9mm | 15.2 | 21 |
| February | 7° | 0.8° | 50.5mm | 14.2 | 28 |
| March | 11° | 2.5° | 53.2mm | 14 | 43 |
| April | 15.5° | 5.1° | 46.1mm | 11.1 | 63 |
| May | 19.2° | 8.6° | 70.7mm | 12.6 | 72 |
| June | 22.7° | 11.9° | 80.7mm | 12.6 | 75 |
| July | 24.2° | 13.7° | 84.5mm | 13.8 | 72 |
| August | 24.1° | 13.6° | 83.4mm | 13.8 | 72 |
| September | 20.2° | 10.5° | 61.6mm | 11.8 | 76 |
| October | 15.4° | 7.6° | 59.2mm | 13.2 | 59 |
| November | 9.8° | 4.1° | 59.9mm | 14.3 | 39 |
| December | 6.5° | 1.6° | 57.4mm | 15.9 | 26 |
January in Bonn averages a daily high of 5.5°C with nights around 0.4°C. Expect roughly 15.2 wet days totalling 57.9mm. A hard month to visit for comfort alone.
February in Bonn averages a daily high of 7°C with nights around 0.8°C. Expect roughly 14.2 wet days totalling 50.5mm. A hard month to visit for comfort alone.
March in Bonn averages a daily high of 11°C with nights around 2.5°C. Expect roughly 14 wet days totalling 53.2mm. Demanding conditions — pack for it and plan indoor options.
April in Bonn averages a daily high of 15.5°C with nights around 5.1°C. Expect roughly 11.1 wet days totalling 46.1mm. Generally workable, with some weather to plan around.
May in Bonn averages a daily high of 19.2°C with nights around 8.6°C. Expect roughly 12.6 wet days totalling 70.7mm. Generally workable, with some weather to plan around.
June in Bonn averages a daily high of 22.7°C with nights around 11.9°C. Expect roughly 12.6 wet days totalling 80.7mm. Comfortable conditions for being outdoors all day.
July in Bonn averages a daily high of 24.2°C with nights around 13.7°C. Expect roughly 13.8 wet days totalling 84.5mm. Generally workable, with some weather to plan around.
August in Bonn averages a daily high of 24.1°C with nights around 13.6°C. Expect roughly 13.8 wet days totalling 83.4mm. Generally workable, with some weather to plan around.
September in Bonn averages a daily high of 20.2°C with nights around 10.5°C. Expect roughly 11.8 wet days totalling 61.6mm. Comfortable conditions for being outdoors all day.
October in Bonn averages a daily high of 15.4°C with nights around 7.6°C. Expect roughly 13.2 wet days totalling 59.2mm. Generally workable, with some weather to plan around.
November in Bonn averages a daily high of 9.8°C with nights around 4.1°C. Expect roughly 14.3 wet days totalling 59.9mm. Demanding conditions — pack for it and plan indoor options.
December in Bonn averages a daily high of 6.5°C with nights around 1.6°C. Expect roughly 15.9 wet days totalling 57.4mm. A hard month to visit for comfort alone.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Bonn peaks at 76.
Based on 30 years of records, May–September scores highest for comfort in Bonn, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 24.2°C.
July is the wettest, averaging 84.5mm of rain across roughly 13.8 wet days.
January is the coolest month, with average daily highs around 5.5°C.